It is provided a grayscale voltage debugging method for debugging a display device including a white subpixel, including a first step of, in a state where the white subpixel is disenabled and subpixels in other colors are enabled, adjusting a respective to-be-adjusted grayscale voltage applied to each of the subpixels in other colors, so that a first actually-measured Gamma curve corresponding to the respective adjusted grayscale voltage is located within an acceptable range of a standard Gamma curve, and a second step of, in a state where the white subpixel and the subpixels in other colors are all enabled, acquiring a second actually-measured Gamma curve and in the case that the second actually-measured Gamma curve is not located within the acceptable range, changing the respective adjusted grayscale voltage to obtain a new respective to-be-adjusted grayscale voltage, and returning to the first step.